chore: create a docker image of testnet with RLN Memberships

[stubbsta]

Background

This would speed-up ad-hoc testing by nwaku, js-waku and DST a great deal

Details

Create a docker image of an Anvil testnet where the RLN contract is deployed with a set amount of Memberships already registered

Acceptance criteria

• image available on harbor
• README with list of membership accounts and credentials
• verify image with waku-sim